1. Field of the Invention
The present invention relates in general to the signaling needed to enable a mobile phone to have at least partial control over which antenna(s) within a coverage area of at least one base station and under control of a scheduling unit are to be used for transmissions to the mobile phone.
2. Description of Related Art
In the wireless communications field, there has been an interest in making sure that the appropriate antenna(s) from within one or more base stations are used for transmitting and receiving signals to and from a mobile phone (user equipment (UE)). For example, in U.S. Pat. No. 6,421,543 there was disclosed a base station that receives cellular radiotelephone communication energy from a mobile phone on an antenna array, processes the received communications energy to produce at least three processed radiotelephone communications signals, and selects at least two of the processed signals for decoding in a conventional decoder. This scheme involves the selection of different received signals at a base station that incorporates a fixed beamforming array antenna.
On the other hand, there are several documents which discuss the potential performance gain from enabling a base station to select antenna(s) for transmitting signals to a mobile phone. For instance, the base station can obtain information from an uplink transmission and then estimate the direction a mobile phone is moving and use that information to select the appropriate antenna(s) which should be used for future transmissions to that mobile phone. The documents include:                D. Gore, R. Heath, and A. Paulraj, Statistical antenna selection for spatial multiplexing systems, In Proc. IEEE Int. Conf., on Communications, New York, April 2002, p. 450-454.        D. Gore and A. Paulraj, Statistical antenna subset selection with space-time coding, IEEE Trans. on Signal Processing, 50:2580-8, Oct. 2002.        R. Narasimham, Spatial multiplexing with transmit antenna and constellation selection for correlated MIMO fading channels, IEEE Trans. on Signal Processing, 51(11):2829-38, Nov. 2003.        
As can be seen, antenna selection is not in itself a new concept. However, it would be desirable if the mobile phone itself had at least partial control over which antenna(s) from the antenna configuration associated with the base station should be used for transmissions. For instance, this capability would be desirable because the mobile phone itself has the best knowledge of its interference environment, which it can monitor, rather than having the base station estimate/predict the mobile phone's interference environment. In addition, as the concept of a mobile phone being served by antenna(s) from one base station corresponding to a single cell has been changing such that a cell may now consist of multiple antennas distributed throughout a coverage region and connected to one or more base stations. In this scenario, the antennas that communicate to the mobile phone need to be determined, and the corresponding signaling also needs to be devised. These particular needs and other needs are satisfied by the present invention.